Based on a fluid dynamical concept of the mechanics of the pleural space, a combined research program of theoretical calculations, model experiments and animal experiments is being carried out which investigates the time history and spatial distribution of pleural pressure and stress on the lungs, under a variety of conditions. The conditions include stationary and moving chest wall and diaphragm, and upright, supine and inverted positions. The emphasis is to obtain a unified dynamical picture of pleural space mechanics, and to investigate the coupling of the pleural space mechanics with the lung mechanical structures, and the distribution in the lungs, and to infer lung mechanical properties from external measurements, it becomes increasingly necessary to obtain this dynamical information.